Patent Literature 1 describes a card processing device including a magnetic head configured to perform reading of magnetic information from a magnetic recording medium and writing of magnetic information to a magnetic recording medium. In the card processing device (a magnetic recording medium processing device) according to Patent Literature 1, the magnetic head includes a core that is provided with a gap, a reading coil and a writing coil that are wound on the core, a demodulation circuit configured to demodulate an analogue signal output from the reading coil, and an encryption circuit configured to encrypt a demodulated signal output from the demodulation circuit. The magnetic head detects variations of a magnetic field when a magnetic card (magnetic recording medium) passes the gap, and outputs a signal encrypted by the encryption circuit. An output terminal from which the encrypted signal (a read signal) is output and an input terminal to which a writing signal (write signal) is input are provided at the magnetic head.